The objective of this research proposal is to delineate differences in the regulation of cell division between lymphocytes obtained from healthy donors and from patients with chronic lymphocytic leukemia (CLL). The role exerted by cyclic AMP in relationship to cell growth induced by mitogens was investigated in both cell types. The intracellular levels of cyclic AMP were 3-fold greater in normal lymphocytes than in CLL cells. Furthermore, cyclic AMP levels fluctuated as a function of cell division in normal lymphocytes but not in the leukemic ones. Sodium periodate stimulated both normal and CLL lymphocytes to divide. This response could be manipulated by treatment of cells with neuraminidase or trypsin. When normal lymphocytes were treated with sodium periodate, a soluble lymphocyte growth factor was released or produced. These studies provide new insights into how cell division is controlled in lymphoid cell populations. BIBLIOGRAPHIC REFERENCES: T.M.Monahan, N.W. Marchand, R.R. Fritz, and C.W. Abell. "Cyclic Adenosine 3', 5'-Monophosphate Levels and Activities of Related Enzymes in Normal and Leukemic Lymphocytes" Cancer Res. 35: 2540, 1975. T.M. Monahan, R.R. Fritz, and C.W. Abell. "Sodium Periodate Stimulation of Human Lymphocytes. A Comparison between Normal and Chronic Lymphocytic Leukemia Lymphocytes" Exptl. Cell Res. 93: 505, 1975.